Casting blank has scales existing on surface after being heated by reheating furnace and before being transferred into a rolling mill, and the scales are need to be duly removed on-line. The main difficulties in surface descaling are as follows: 1. The surface temperature of the casting blanks is very high, that is, between 1100□ and 1250□, and the oxide layer thereof is so thick that it is hard to clean them clearly by existing methods; 2. Adhesivity between scales generated on surface of continuous-casting blanks such as stainless steel, silicon steel, iron-nickel alloy and the continuous-casting blank body is too strong to clean only by high-pressure water; 3. Hot rolling production line is sensitive to temperature of the blanks, and increasing amount of water may result in larger temperature drop of the continuous casting blank, which is harmful to the follow-up rolling.
The current common type of descaling is to clear the scales on the surface away by high-pressure water of more than 18 MPa, i.e. high-pressure water descaling. This type of descaling has the following disadvantages: 1. A large quantity of water is needed, and the temperature of the surface of the continuous-casting blanks drops sharply, which causes edge cracks on many high alloy products during the follow-up rolling; 2. High-pressure water descaling utilizes nozzles, and it is usual that the scales are not obliterated clearly, thereby resulting in that scales are pressed into the blank during follow-up rolling; 3. For high alloy steel (such as silicon steel, stainless steel, iron-nickel alloy), high-pressure water cannot clear non-ferric oxides (silicon oxide, chromic oxide, nickel oxide and the like), which substantially affects the surface quality of these products.